Cables Not in Trouble

by Arvid Grant, Principal-Consulting Engineer; Arvid Grant Associates, Washington, DC,


Serial Information: Civil Engineering—ASCE, 1991, Vol. 61, Issue 5, Pg. 61-63


Document Type: Feature article

Abstract: Cable-stayed bridges in the U.S. are not, contrary to reports widely disseminated in the press several years ago, about to fail from corrosion. The design, in which primary cables support the deck directly rather than indirectly via suspenders from two main cables, has been used for about 200 or more bridges worldwide. In 1990, detailed engineering investigations of the conditions of the cables in some of the earliest U.S. cable-stayed bridges found no damage. These included bridges built in the 1970s in Alaska at Sitka Harbor and near Skagway, at Meridan in California, and at Pasco, Wash. The first three are steel girder structures supported by galvanized-wire structural-strand cables with traditional cast-zinc anchorages. At Pasco, built in 1972-78, the anchorages are also cast-zinc, but the ungalvanized wires are encased in black polyethylene pipe that is filled with portland cement grout and wrapped with white tape. In 1990, the pipes were rewrapped with a polyvinyl fluoride tape; inspection at that time revealed no pipe splits or damage. The wires were clean in the same condition as they had been 12 years earlier. The implication is that proper design and meticulous quality control during construction (especially cable manufacture) results in bridges that promise very long, even indefinite, service.

Subject Headings: Bridge inspection | Bridges | Cable-stayed bridges | Construction | Design | Quality control | Structural reliability

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